Intake Manifold Change-Over, Checking

Intake manifold change-over, checking (A6 models)

Only perform the test when there is a lack in performance or a DTC was registered.

The change-over of the intake manifold from the long to the short intake path is dependent on speed.

Intake manifold change-over, function

- Connect vehicle diagnostic, testing and information system VAS 5051 or VAG 1551 Scan Tool and select engine electronics control unit 1 with "Address word" 01. For this purpose, engine must be running at idle speed.
Connecting VAS 5051 Scan Tool
[1][2]Scan Tool Connecting and Initial Checks

Indicated on display


Rapid data transfer HELP
Select function XX


- Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display


Read measured value block 08
Enter display group number XXX


- Press keys 0, 9 and 5 for "display group number 95" and confirm entry with Q key.

Indicated on display


Read measured value block 95 ->
1 2 3 4


- Check display values for intake manifold change-over.

Display Group 95:

- Check display in display zone 4.
Specified value: "IMC-V OFF"







- Increase engine speed to following speed to initiate intake manifold change-over.

Engine speed Vacuum unit
approx. 3400 rpm Stage 1 lower vacuum unit
approx. 5300 rpm Stage 2 upper vacuum unit

Display Group 95:

- Check whether correct vacuum unit is actuated with relevant speed.

If "stage 1 or 2" is displayed but the intake manifold change-over is not initiated (vacuum units must not be actuated) check the following components:

- Check solenoid valves for intake manifold change-over.
Intake Change-Over -N156- & Tuning (IMT) Valve 2 -N261-